Inventor General

## Inventor General

*dave-gnus
Message 1 of 2 (6,373 Views)

# beginner trying to make perfect wire tetrahedron

6373 Views, 1 Replies
10-31-2002 06:07 AM
Howdy, I'm a beginner using IV4. I'm trying to construct an imaginary
part: a perfect tetrahedron, 200mm on a side, made out of 1mm diameter
wire. Each vertex of the tetrahedron should have three wire edges
coming together at a point.

I can make a triangle no problem:

1. sketch a rough triangle
2. make dimensions d1 and d2 both equal d0
3. return and create a work plane perpindicular to original sketch:
a. select "work plane" tool
b. select one edge of triangle
c. select one vertex of that edge
5. create a sketch on the new work plane
6. "project geometry" the coincident vertex into the sketch
7. create a center-point circle centered on the vertex
8. return and "sweep" the circle around the triangle

I would like, as a next step, to create a work plane at the right
angle to the plane of the triangle, coincident with the center of one
of the lines. Unfortunately, I can't figure out how to do this. The
work plane reference page in help says that to create a work plane at
an angle, I select two parallel faces and enter an angle into an edit
box. But since I don't have two parallel faces, I don't get an edit
box. I've searched for another way to do the edit box, but haven't
found it. I figure there must be a constraint-based way to acheive
the tetrahedron.

I have tried hacking my way to a solution:

1. sweep out triangle as above
2. create a work plane on the interface between the wires at a vertex
by selecting three points around the edge of the vertex interface
3. create a sketch in this work plane
4. project the vertex into the work plane
5. create a center circle with radius equal to the length of an edge
(200mm). This is purely for construction purposes
6. return and repeat steps 2-5 for a different vertex
7. project circle created in step 5 into current sketch
8. draw a point at the intersection
9. return and create a work plane as the combination of the point
from step 8 along with two vertices from the triangle in step 1
10. create a sketch in the new work plane, project the vertices, draw
another pair of edges, return, create a 1mm circular profile and
sweep
11. repeat step 9 with another pair of vertices
12. repeat step 10 in the new work plane

This does make a tetrahedron. The problem is that the vertices of the
last step don't line up! I can't seem to make the work plane
intersect the actual endpoints of the original triangle.

I imagine that I could just put three triangles together with
constraints in an assembly. But it seems like I should be able to
acheive the same goal by just creating a part. Can anyone offer a
simpler way to acheive this goal?

Thanks,
Dave
*KJohnson
Message 2 of 2 (6,373 Views)

# Re: beginner trying to make perfect wire tetrahedron

10-31-2002 08:50 PM in reply to: *dave-gnus
In the sketch that you want it construct a construction line from mid point
to mid point. Change the style in the drop down to construction. STart a
line. hover and move the cursor over one of the sketch lines until the dot
turns green this will be the midpoint. Now attach the other end to the
opposite sketch line. You may have to but a horiz or vert constraint on the
new line. Exit the sketch. Start a workplane and select the construction
line you just made and a plane that is 90 deg to what you want. You should
be able to specify an angle now. Good luck

Kathy Johnson

wrote in message news:m3n0ouw9c6.fsf_-_@bfnet.com...
> Howdy, I'm a beginner using IV4. I'm trying to construct an imaginary
> part: a perfect tetrahedron, 200mm on a side, made out of 1mm diameter
> wire. Each vertex of the tetrahedron should have three wire edges
> coming together at a point.
>
> I can make a triangle no problem:
>
> 1. sketch a rough triangle
> 2. make dimensions d1 and d2 both equal d0
> 3. return and create a work plane perpindicular to original sketch:
> a. select "work plane" tool
> b. select one edge of triangle
> c. select one vertex of that edge
> 5. create a sketch on the new work plane
> 6. "project geometry" the coincident vertex into the sketch
> 7. create a center-point circle centered on the vertex
> 8. return and "sweep" the circle around the triangle
>
> I would like, as a next step, to create a work plane at the right
> angle to the plane of the triangle, coincident with the center of one
> of the lines. Unfortunately, I can't figure out how to do this. The
> work plane reference page in help says that to create a work plane at
> an angle, I select two parallel faces and enter an angle into an edit
> box. But since I don't have two parallel faces, I don't get an edit
> box. I've searched for another way to do the edit box, but haven't
> found it. I figure there must be a constraint-based way to acheive
> the tetrahedron.
>
> I have tried hacking my way to a solution:
>
> 1. sweep out triangle as above
> 2. create a work plane on the interface between the wires at a vertex
> by selecting three points around the edge of the vertex interface
> 3. create a sketch in this work plane
> 4. project the vertex into the work plane
> 5. create a center circle with radius equal to the length of an edge
> (200mm). This is purely for construction purposes
> 6. return and repeat steps 2-5 for a different vertex
> 7. project circle created in step 5 into current sketch
> 8. draw a point at the intersection
> 9. return and create a work plane as the combination of the point
> from step 8 along with two vertices from the triangle in step 1
> 10. create a sketch in the new work plane, project the vertices, draw
> another pair of edges, return, create a 1mm circular profile and
> sweep
> 11. repeat step 9 with another pair of vertices
> 12. repeat step 10 in the new work plane
>
> This does make a tetrahedron. The problem is that the vertices of the
> last step don't line up! I can't seem to make the work plane
> intersect the actual endpoints of the original triangle.
>
> I imagine that I could just put three triangles together with
> constraints in an assembly. But it seems like I should be able to
> acheive the same goal by just creating a part. Can anyone offer a
> simpler way to acheive this goal?
>
> Thanks,
> Dave

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